import type { Directive, DirectiveBinding } from 'vue';

/**
 * v-dialogDrag 弹窗拖拽指令
 */
export const dialogDrag: Directive = {
  mounted(el: HTMLElement, binding: DirectiveBinding) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header') as HTMLElement;
    const dragDom = el.querySelector('.el-dialog') as HTMLElement;
    if (!dialogHeaderEl || !dragDom) return;
    
    dialogHeaderEl.style.cursor = 'move';

    // 获取原有属性 (备份)
    const sty = (dragDom as any).currentStyle || window.getComputedStyle(dragDom, null);
    let moveDown = false;
    dialogHeaderEl.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft;
      const disY = e.clientY - dialogHeaderEl.offsetTop;

      // 获取到的值带px 正则匹配替换
      let styL, styT;

      // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
      if (sty.left.includes('%')) {
        styL = +document.body.clientWidth * (+sty.left.replace(/%/g, '') / 100);
        styT = +document.body.clientHeight * (+sty.top.replace(/%/g, '') / 100);
      } else {
        styL = +sty.left.replace(/px/g, '');
        styT = +sty.top.replace(/px/g, '');
      }

      document.onmousemove = function (e) {
        moveDown = true;
        // 通过事件委托，计算移动的距离
        const l = e.clientX - disX;
        const t = e.clientY - disY;

        // 移动当前元素
        dragDom.style.left = `${l + styL}px`;
        dragDom.style.top = `${t + styT}px`;
      };

      document.onmouseup = function (e) {
        if (moveDown) {
          document.onmousemove = null;
          document.onmouseup = null;
          moveDown = false;
        }
      };
    };
  }
};

export default dialogDrag; 